#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>

int main(void)
{
	double a = 0;
	double b = 0;
	double num1 = 0;
	double num2 = 0;
	for (int i = 1.0; i < 99.0; i += 2.0)
	{
		a = 1.0 / i;
		num1 = num1 + a;
	}
	for (int i = 2.0; i < 100.0; i += 2.0)
	{
		b = 1.0 / i;
		num2 = num2 + b;
	}
	printf("%f", a - b);
	return 0;
}